Frequency adjusting system



Dec. 11, 1934. HA D E 1,984,301

FREQUENCY ADJUSTING SYSTEM Filed April 18, 1930 2 Sheets-Sheet 1* 4 Z I; Jwuwtmo @0441: Q. $256044 (b rue 2 3440013042 ATTORNEY 1934? LA GEBHARD d AL 1,984,301

FREQUENCY ADJUSTING SYSTEM Filed April 18, 1930 2 Sheets-Sheet 2 2 II E- E 1 I i g I i I i l I l Q W A ATTOkNEY Patented Dec. 11, 1934 FREQUENCY ADJUSTING SYSTEM Louis A. Gebhard and Corrie F. Rudolph, Washington, D. 0.; said Gebhard assignor to Wired Radio, Inc., New York, N. Y., a corporation of Delaware Application April 18, 1930, Serial No. 445,416

8 Claims. (Cl. 250-17) Our invention relates broadly to frequency adjusting systems and more particularly to a frequency changing system for short wave radio transmitters.

One of the objects of our invention is to provide a compact arrangement of frequency adjusting system for short wave transmitters wherein tuning adjustments may be effected simultaneously in a multiplicity of circuits connected with a transmitter.

Another object of our invention is to provide a compact arrangement of frequency changing apparatus in which the inductance in a multiplicity of circuits in the transmitter may be simultaneously changed for adjusting the operating frequency of the transmitter wth a minimum number of controls.

A further object of our invention is to provide a method of mounting a multipilicity of inductance units adjacent the parts of the transmitting apparatus by which selected portions of prearranged stationary inductance units may. be effectively connected in one portion of the transmitter circuits, while other inductance units may be movably shifted into connection with other parts of the transmitter circuits in adjusting the transmitter circuits for operation upon selected frequencies.

A still further object of our invention is to provide a frequency changing system for short wave transmitters in which connections may be simultaneously established between parts of a transmitter circuit and selected fixed inductance units, and connections established by movably interchanging other inductance units in other portions of the transmitter circuit.

Other and further objects of our invention reside in the assembly of the tuning elements in a high frequency transmitter as set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 schematically illustrates the arrangement of the fixed inductance units and movable inductance units in a high frequency transmitter; Fig. 2 is a side elevation showing the assemblyof the fixed removable inductance units in the frequency changing portion of a short wave transmitter constructed according to our invention; and Fig. 3 is a detailed cross-sectional view showing one arrangement of fiuid cooled fixed inductance units employed in the transmitter system of our invention.

In high frequency radio transmitters covering a relatively wide frequency band it is necessary to arrange inductances both in the input and output circuits of each stage of amplification. These inductances must be changed for operation of the transmitter at different frequencies. The frequency change operation must often be made quickly and we have therefore designed a frequency change system for high frequency transmitters wherein both the input and output inductance coils may be switched simultaneously into or out of the amplifier circuits. We have found that a more compact arrangement may be made within the transmitter frame by mounting certain of the inductance coils for rotation on a selecting frame whereas others of the coils are mounted in fixed position and are provided with taps to which selected connection may be made by the simultaneous movement of the switching mechanism.

It is particularly desirable that coils consisting of tubular conductors to conduct cooling fluid should be mounted in fixed position. The frequency adjusting system here disclosed is well adapted for use with the system disclosed in the Reissue Patent No. 18,070 to Louis A. Gebhard, wherein inductances 11 and 18 are to be interchanged by the system disclosed in the present application.

Referring to the drawings in more detail, reference character 1 designates the tuning condensers for the transmitter which are supported concentrically around the electron tube jackets 2, which jackets carry electron tubes 3. The assembly of tube jackets, electron tubes, and tun ing condensers is supported by means of insulated frame 4 extending from the framework of the radio transmitter. The input circuit inductance coils are indicated at 5 carried by a rotatable frame 6. The frame 6 has a plurality of radially extending arms which support inductances of selected frequency characteristics in the ends thereof. Each inductance 5 is provided with radially extending blades which may be brought into connection with sets of fixed blades 8 which may connect to the input circuits of the high power tubes 3 through circuits including the input tuning condenser 9 and the tuning condensers 1. The changing of the coils 5 is accomplished by means of the crank 10 which connects to shaft 7 which in turn supports the frame 6. The shaft 'Iis suitably journaled in the frame 30 of the a tures 1.

11. An auxiliary shaft 12 is driven through the bevel gear system 11 and imparts motion to bevel gear system 13 which drives shaft 14. The shafts 12 and 14 are suitably supported in bearings mounted upon the frame 30 of the transmitter. The shaft 14 is broken by insulated portions 15 and 16 which are mounted in bearings 19 and 20'supported from the condenser struc- The insulated portions 15 and 16 are interconnected by link member 1'7. The insulated portion 16 of the insulated shaft carries the shaft portion 18. The switch bladesE-Zhandiflla are carried by the link portion 17..and the shaft 18. The switch blades 21 andr21a-l1aveflexible.

brushes 22 and 22a supported thereon and'these brushes successively engage with contacts 23 and 23a on the output inductance coils 24. We have illustrated a multiplicity ofoutput coils' 24, 24b and 240 fixed in position with respect to the switching apparatus and arranged with sets of contacts by which aiselected inductance maybe connected in thetransmittercircuit. z-Coils :24 may consist of only three turns approximately one foot in diameter, in short-waveatransmitters. In such short-wave apparatus, it is highly important that-the coil leads be very short, and the construction which we haveprovided is very effective for this purpose,as wellasproviding-a compact arrangement which can be 'mountedin small space. In push-pullsystems of the type shown in the ReissuePatent No. 18,070:of Louis A. Gebhard, datedMay 19, 1931, itis-important that the cross connectionsof the inputshallbe in close proximity to the .tube units -,and:symmetrically arranged withrespect thereto,-and the system of our invention ;.serves :this purpose :to good advantage.

For the purpose of explaining .our invention, we have shown three-end coils at-24, 2lb,and.2elc, each of the coils havingseparate sets of contacts with which the moving switch bladeymay establish connection. The inductance coil 24 has radially positioned contacts 23 and 23a-and is -;sup ported by bracket l2f on support 27 which .is attached to the frame 30. :Bracket 12Gb extends from the support 27 and carries the inductance coil 241). Sets of contacts 23b arecarried' by the inductance coil 24?) arranged at such an angle with respect to the movement of the switch blades 21 and 21a as will enable sliding contact to be established with the switch blades. Inductance coil 240 is carriedby bracket 26c which extends laterally from the support 27 on frame 3.0. Contacts 23cextend from theinductance .24cin such an angular direction that connectionamaybe established by angular movement of theasets of switch blades 21 and 21a to selected positions. Thebrackets 26, 26b, and 260 are all suitably insulated in order tosuspend the associated inductance coils in proper relation withzthe frame of the transmitter. The'bracke'ts are of varying lengths in. order tosupport the inductance coils in an arcuate' path about therotatable members 1-7 and 18. In one position, the switch blades 21 and 21a are not connected with contacts on "an inductance coil. Ihis position-isshown in dotted line at 28 in Fig. '1, and in thisposition a coil not shown in the drawings is connected between the anodes of the twotubes 3, and the stationary mounting of-the several inductance coils '24, 2gb, and 240 enables these coils to be fluid cooled as illustrated, for example, 'in'Fig. 3 where-the coil 24 is shown in cross-section as constituted by hollow tubingthrough whichcooling water circulates. The lowest frequency range of the transmitter is established by the permanently connected coil which connects between the anodes of the tubes 3. The other frequency settings for the transmitter are obtained by the parallel connection of the selected inductance in some one of the other coils 24, 24b, or 240 in accordance with the selected transmission frequency.

The operation of the brushes 22 :and:22a is timed through the system of shafts l2 and 12a so that the movement of the switches is coordinated with the shifting in position of the inductancesfi. Ihatis to say, simultaneous control in the movement of the inductances 5 into or out of the transmitter circuit is timed with respect "to the corresponding movement of the brushes 22 and 22a. 'Alshift'inposition of the movable inductance coils 5 is accompanied by a similar shift nin.position.of.thebrushes 22 and 22a so that a particular. coil 5 is selected simultaneously with 'the connection of a selected inductance 24, 24b,

tended-other than are imposed by the scope of the. appended claims.

What we .claim as new anddesire-to secure by Letters. Patent of the' United. Statesis as follows:

'1. In a high frequency transmissionsystem, electron tube stages'having input terminals and output termina1s, a multiplicity of tunable circuits, 'a plurality .of. fixedoutput inductance units of different frequency characteristics, contacts extending from .each .of said fixed inductance units,.-a .selective switchconnectibleto the contacts.ofiany,oneofsaidfixed inductance units, a movableframe structure, input inductance units each having-projecting contactsithereon and supported by said movable frame structure, a, set of fixed contacts engageable with .the contacts carried by the input inductances on said movable frame .structure, circuits interconnecting said switching .system and said fixed contacts,-the

number of said output inductanceunits and: contacts therefor being one less" than the number of said inputiinductances, and a control system interconnecting said switching system and said movable frame structure for simultaneously shifting said movableframestructure and operating said switching system for the selective operation ,ofssaid transmitter circuits on a particular signaling frequency, for connecting-tone of saidoutputtcoils .tosaid :switch for each position =except one ofsaid movable frame which connects an input coil to said fixed contacts.

.2. The combination in accordance-with claim 1 in which said output inductance units each comprise alhelicalfiuidcooling tubing.

.3, The combination inaccordance with claim 1 in which said soutput inductance units-each comprise ;a fluid-cooling helical-tubing and in which sai'd control system 'comprisesgaiplurality .of rotatable shafts interconnected by :ge'aring, and a manual device for imparting rotary motion to said shafts.

4. A high frequency transmitterconstruction comprising;anelectrontube stage having input and outiautcircuits, ase'lective input inductance system comprising a rotatable frame member carrying a set of helical inductance units for movement through an arcuate path, stationary contacts connected in said input circuit of said electron tube stage and disposed in proximity to said arcuate path, and contacts mounted on each of said inductances for engaging with said stationary contacts when said inductances are moved through said arcuate path for selectively interconnecting desired ones of said inductances in said input circuit; a second set of inductances each carrying contacts thereon, stationary mounting means for supporting said second set of inductances to cause said contacts thereon to project into an arcuate path, said second set of inductances each comprising a helical tubing for the conduction of cooling fluid therethrough, a rotatable contacting device mounted for arcuate movement for selectively engaging said contacts of said second set of inductances for connecting the same in the output circuit of said electron tube stage, and mechanical means for simultaneously and conjointly moving said rotatable device and said rotatable frame member for selectively connecting said inductances respectively in the input and output circuits of said electron tube stage.

5. A combination in accordance with claim 4 in which the number of inductance units in said first mentioned set of inductances is greater than the number of inductances in said second mentioned set of inductances.

6. A combination in accordance with claim 4 in which said electron tube stage includes a condenser partially enclosing an electron tube, and in which said rotatable switching device is supported from said condenser.

7. A combination in accordance with claim 4 in which said electron tube stage includes a condenser structure and in which said rotatable switching device is supported from said condenser structure, said rotatable switching device including a plurality of axially aligned conductive elements electrically insulated from each other.

8. A combination in accordance with claim 4 in which there are a different number of inductances in each of said sets, and in which said electron tube stage comprises a condenser surrounding a high power tube, said rotatable switching device being supported from said condenser and including a plurality of axially aligned contact members electrically insulated from each other, and said mechanical means comprising a plurality of intergeared shafts and a hand crank for actuating the same.

LOUIS A. GEBHARD. CORRIE F. RUDOLPH. 

